FIELD OF THE INVENTION

This invention refers to a multi phased process of obtaining synthesis gas (to be referred from now on as syngas] in a continuous flow; the purpose of this gas is using it as an alternative fuel.

The technical problem that the invention solves is obtaining an alternative gaseous fuel that permits a significant reduction in production costs of thermal energy and also an overall reduction of carbon dioxide emissions into the environment. These reductions are achieved in comparison to the burning of traditional fossil fuels, when used to generate the same ammounts of thermal energy.

The concept of "syngas - cogeneration " ("SGC" method), introduced in the present invention, defines the simultaneous generation and burning, in the same installation, of synthesis gas and the production, by cogeneration, of thermal, electrical or/and mechanical energy. The cogeneration system is formed by the following assembly: a "rotating cavitation/vaporization device", a cylindrical furnace with a reforming tube, a "user boiler", a steam turbine, an electrical power generator and a steam engine.

BACKGROUND OF THE INVENTION

At present, the chemical and energy industries, use already established technologies to produce syngas, such as catalytic reforming with steam, done in reforming kilns. The process of industrial catalytic reforming with steam consists of two main phases. In the first phase, steam is added at a temperature of about 450-500 °C and a pressure of 25-30 bar to complex hydrocarbons, they then decompose into methane, hydrogen, carbon monoxide and carbon dioxide. In the second phase, throughout the reforming mixture, methane reacts with water, in the presence of the catalyst, at temperatures of about 800- 900 °C and a pressure of 25-30 bar. As a result, after these two phases, syngas is obtained. Generally, syngas consists of hydrogen and carbon monoxide in varying proportions. The hydrocarbon most used to obtain syngas is natural gas.

The general equation is: C _n H _ra + nH ₂ 0 *→ (n+m/2)H2 + nCO

Technological processes at industrial level are fine-tuned, but some economic and financial characteristics could be made more efficient, such as: classic fuel consumption, necessary for maintaining strong endothermic reforming reactions; the presence of expensive catalysts; the high cost and technical complexity of the equipment needed for the technology. These economic and financial characteristics can be improved by:

- The exclusion of the catalysts from the technological process; - The reduction of classic fuel consumption, used to produce the thermal energy needed to generate the strong endothermic reactions of steam reforming;

- ensuring that the reforming reactions develop at lower pressures;

- ensuring that the technological process develops with equipment less complex;

- Simultaneous production of syngas and cogeneration of thermal, electrical and/or mechanical energy, in the same plant/installation;

A known method, with certain aspects close to the present invention, for producing syngas by steam reforming various carbonaceous materials (CA 2581288) is comprised of the following steps. Raw materials are supplied into a reforming rotary kiln, equipped with external heating means, in which the products are thoroughly mixed and heated to temperatures of 650-1100 °C, in the presence of water or steam. The thermal energy used for constant heating of the reforming furnace and the time the raw material spends in the furnace should allow the level of reforming to be as close to 100% as possible. Following the completion of the thermochemical reforming reactions with steam, syngas is obtained, which is generally composed of hydrogen and carbon monoxide. This process, however, presents some disadvantages. It requires a high consumption of classic fossil fuels in order to maintain the necessary temperatures in the kiln to bring the facility from "off state to "syngas generation/on" state. It also requires relatively complex and expensive equipment to achieve the technological process.

From the current state of technology, it is known, that in order to obtain one Gcal/h of thermal energy, through known procedures, a certain quantity of classic liquid hydrocarbons, ranging from 60 to 120 1/h, is used. This quantity varies depending on the caloric power of the fuel and on the performance of the burning equipment.

SUMMARY OF THE INVENTION

The process of producing syngas, in a continuous flow, through cold "cavitation", pyrogenic reaction and sequential non catalytic reforming of hydrocarbons with steam at high temperatures, according to the present invention, is comprised of the following steps.

The formation of a continuous flow of mixture of water and liquid fuels (complex hydrocarbons), the weight ratio of the two components ranging from 4:1 to 8:1. The mixture is achieved by injecting a classic fossil fuel into the flow of water. This liquid mixture is fed into the "rotating cavitation/vaporization device". The "rotating cavitation/vaporization device", through intense homogenization and gasification, almost instantaneously generates a gaseous mixture of water and hydrocarbons, in a continuous flow. This is achieved through the vortex currents and "cavitation" process affecting the fed liquid mixture. As a result, we obtain a gas mixture composed of minuscule droplets of primary hydrocarbons and newly formed hydrocarbons, uniformly dispersed within the water vapor mass. The mixture will have a temperature of 150-250 °C and a pressure of 0.4-0.5 MPa.

The gaseous mixture thus formed is continuously introduced into the metal double mantle/shell of a horizontal cylindrical furnace. The furnace is designed as a cylinder within a cylinder. The space in the inner cylinder forms the furnace burning area. The space between the inner and outer cylinder forms the technological zone for heating the gaseous mixture flow to the temperatures necessary for the execution of pyrolysis reactions. The inside of the furnace is heated by burning classic fossil fuels via a mixed burner (double injector), located at the head of the furnace. Hot combustion gases are discharged through the end of the furnace directly into the "user boiler" (an "user boiler" is a boiler that uses the hot combustion gases) burning area, the lid of the "user boiler" is coupled to the furnace. The combustion of the classic fossil fuel will provide the high temperatures in the furnace burning area for a short period of time. This is only required to heat the inner mantle/shell of the furnace and start up a continuous process of syngas generation and combustion, then the classic fossil fuel supply to the burner is interrupted. The furnace heating is further provided entirely only by the combustion of syngas produced according to the outlined process. The double mantle/shell of the furnace acts as a radiating heat exchanger, it is the technological zone where the gaseous mixture is superheated in a continuous flow to a temperature of about 1100-1200 °C. This temperature is sufficient to achieve thermal steam pyrolysis reactions of hydrocarbons at atmospheric pressure without catalyst. This temperature is maintained by burning classic fossil fuels or syngas inside the furnace, it is then transferred to the gaseous mixture inside the double mantle/shell of the furnace. The movement of the gaseous mixture through the toroidal cylindrical zone of the cylindrical furnace mantle/shell has got a direction parallel with that of the burning gases. As a result of this high heating, the hydrocarbon (primary and newly formed during the "cavitation treatment" from the previous phase) droplets from the mixture are subjected to "primary" and "secondary" pyrolysis reactions, after which takes place their thermal decomposition into carbon, hydrogen and other new hydrocarbons that have a relative higher stability at these temperatures. t

The general equation is: C _n H _m ^> xC + yH ₂ +C _n -xH _n -2y

In this phase the steam in the mixture acts to prevent the coking effect, which can occur as a result of "secondary" high-temperature pyrolysis. This is achieved by the fluidization of carbon from the zone where pyrogenic reactions take place and at the same time by carrying out the endothermic reaction of decomposition of a portion of the steam from the mixture into the so-called "water gas",

C + H ₂ 0 = CO + H ₂ after which carbon monoxide and hydrogen is obtained.

A key role, in achieving the speed and depth/totality of hydrocarbon (primary and newly formed) thermal decomposition reactions from the gaseous mixture and to obtain "water gas", in addition to the high temperatures involved, is the fact that the hydrocarbons were uniformly dispersed in very small drops in the mass of water vapor in the previous stage of the process, thus obtaining the same positive effects for the completion of thermochemical reactions as in the case of circulating fluidized bed gasification, a widely used method in industry .

The complex gaseous mixture thus formed and composed generally of hydrogen, carbon monoxide, newly formed different hydrocarbons, and the rest of the steam, is fed into a reforming tube, which is located in the furnace burning area.

The complex gas mixture, during its movement through the reforming tube, in a direction opposite to the burning gases in the furnace, is overheated to a temperature of about 1400- 1600 °C by the heat of the hot gasses in the flame of the furnace. This is the temperature necessary for hydrocarbon reforming reactions without the use of catalysts. These temperatures allow performing non-catalytic reforming reactions in the time of 1-2 seconds, a well-documented procedure. As a result, after the completion of the non- catalytic steam reforming reaction at elevated temperatures of the hydrocarbon from the mixture formed in the previous step,

Cn-xH _n -2y + (n-x)H ₂ 0 <→ [n-x+(n-2y)/2]H ₂ + (n-x)CO and the conversion reaction of carbon monoxide with steam, CO + H ₂ O ^ H ₂ + C0 ₂ at the exit of the reforming tube, syngas is obtained, in continuous flow, The obtained syngas is generally composed of hydrogen, carbon monoxide, carbon dioxide, with a high ratio of hydrogen/carbon monoxide.

The syngas is further directed to the supply circuit of the mixed burner (11) to be lit by the ignition system of the burner and burned. Primary and secondary combustion air is provided by the burner fan. The resulting flame temperature from burning syngas, as an alternative fuel, is over 2000 °C. After the burning of syngas starts, classic fuel supply to the burner can be interrupted. Further heat generated from the burning of syngas is used both to maintain the high temperature in the cylindrical furnace burning area (needed for pyrolysis and reforming reactions, in order to generate the syngas in a continuous flow) and to cogenerate (a CHP process) thermic energy (by means of the "user boiler"), electrical or/and mechanical energy (by means of the assembly consisting of a cylindrical furnace, a reformer tube, a "user boiler", a steam turbine, an electrical power generator and a steam engine). By applying the technological process, according to the invention, we achieve the following advantages:

- the drastic reduction (several times) of the costs of generating thermal energy; the syngas, as an alternative fuel, replaces classical fossil fuels with the hydrogen obtained from water, while energy efficiency from burning syngas is higher than that from traditional burning of a classic liquid fuel;

- the technological equipment, used in the installation that produces syngas, is relatively small in size and has reduced technical complexity, which also reduces the manufacturing costs and requires smaller investments; - the simplicity in terms of technological process and the exclusion of the need to store syngas, because it is fully lit and burned, presents much lower risks of damage or accidents during plant operation;

- the absence of lime scale forming in the "rotating cavitation/vaporization device" because "classic" heating elements necessary to vaporize water are not used, the water used as raw material in the production of syngas does not require chemical pretreatment and can be of any kind (industrial, waste, salted, etc.);

- the thermal energy generated from the combustion of the syngas, if obtained from water mixed with biodiesel or vegetable oils, represents a renewable energy source, as biodiesel or vegetable oils are considered renewable energy sources and the water used in the process is regenerated by the oxidation (combustion) of hydrogen from syngas and can be found in the exhaust emissions in form of water vapors, which can be condensed to restore the amount of water initially used to form the mixture;

- the significant reduction of carbon dioxide emissions into the environment, when syngas is used as an alternative fuel, compared to traditional burning of classic liquid fuels, while generating the same amount of thermal energy, as syngas is a fuel with a higher content of hydrogen and lower of carbon and only water vapors are formed after the burning (oxidation) of hydrogen from syngas.

DESCRIPTION OF THE DRAWINGS Figure 1 represents the diagram of the installation for obtaining syngas and production of thermal power through cogeneration.

Figure 2 represents a section of the cylindrical furnace.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following the invention will be described in detail with reference to Picture 1 and Picture 2, which show schematically the installation employed for carrying out the process according to the invention. The following example illustrates the invention without limiting it.

The process begins with the formation of a mixture of water and liquid fuels (complex hydrocarbons), the weight ratio of the two components can vary from 4:1 to 8:1. The ratio chosen depends on the percentage quantity of carbon in the fossil fuel used: the higher it is, the greater may be the ratio. In order to form the mixture, through a pipe-line (1), by means of an electric pump (4), water is pumped from a non-pressurized reservoir (not shown). In the tank there is atmospheric pressure and the water temperature is at least +5 °C. Using an injector (3), directly into the water flow, liquid fuel is injected in order to create a mixture of the desired ratio. Liquid fuel is sucked up through a pipe (2) from a non-pressurized reservoir (not shown). Reservoir pressure is atmospheric and the temperature is the minimum that ensures fluidity. The injector may be a Venturi type, used in different industries for forming a continuous flow of liquid mixture in the desired proportions. The required amount of mixture is achieved by adjusting the pump flow power that can be an industrial water pump.

Pre-homogenization of the flow of mixture obtained is already taking place during pumping when it crosses through the hydraulic pump system (4) (mixer system, gears, etc.). After that, via a discharge pipe (5), pre-homogenized mixture of water and fuel is introduced at a pressure of 0.1-0.2 Mpa, via water pump, into the "rotating cavitation/vaporization device" (6) for an intense mixing and transformation from liquid to gaseous state. In a specific case, for use in the processes of the present invention, may be used the "rotating cavitation/vaporization device" of the type indicated in utility model patent (RU 52976 Ul) which is already made in mass production. It is formed from static disks system and disks that are rotating at a speed of 3000 rev/min. Rotation is provided by an electric motor (7). As a result, the production of the complex gaseous mixture by the "rotating cavitation/vaporization device" is instantaneous and in a continuous flow. That is due to the hydrodynamic forces to which the liquid mixture is subjected to, generally expressed by the extremely high shearing stress exerted on the liquid, the critical velocity turbulent eddies and the process of cavitation. The surface temperature of discs gets up to 300 °C, and the complex gaseous mixture, upon exiting from the "rotating cavitation/vaporization device", has a temperature of about 150 to 250 °C and a pressure of about 0.4. to 0.5 MPa. These critical vortex currents and cavitation phenomena affecting a mixture of liquids, one of which is water and the other a hydrocarbon and the resulting thermodynamic effects associated with these phenomena, are lately subject to fundamental scientific research. There are assumptions, that the thermodynamic processes that occur during the "cavitation bubbles treatment" in a cavitation device can be associated with a process of "micro-cracking" of the hydrocarbon from the mixture, which leads to destructive effects on the chemical bonds at the molecular level to form new hydrocarbons of lower molecular weight and partial splitting of water to form OH-OH radicals, which are highly active oxidizing agents. As "classical" heating elements are not used and lime deposits do not form, water as a raw material in the mixture, does not require any chemical pre-treatment and may be of any type (industrial, waste, salty, etc.,].

The gaseous mixture thus formed is a very fine and uniform dispersion of droplets of hydrocarbons and newly formed hydrocarbons in saturated water vapor according to the proportion of components (water, primary hydrocarbons) present in the previous phase. This proportion is kept uniform throughout the gaseous mixture flow generated by the "rotating cavitation/vaporization device". Keeping constant the proportion of the components in the mixed gaseous mixture stream is very important, because it allows to obtain a syngas with a high homogeneous composition throughout its formation. The combustion of this syngas in the burner will be uniform without pulsations or flame breaking.

From the "rotating cavitation/vaporization device" (6) the gaseous mixture is continuously introduced through a pipe (8) in the double shell of the horizontal cylindrical furnace (25).

The horizontal cylindrical furnace (25) contains: a double mantle/shell composed out of two "cylindrical shells" made out of metals with high heat resistance, the "inner shell" (14) with an exterior diameter d2, an interior diameter d5 and a length b, the "outer shell" (20) with an interior diameter dl and a length a, the ratio between d2:dl is from 0.7 to 0.98, and the ratio between a:b is from 0.5 to 0.95; a lid (13) with an access opening (27); a bottom (21) with an evacuation opening (26) with the diameter d4, the ration between d4:d5 is 0.5 to 0.9; the space between the "inner shell" and the "outer shell", hermetically sealed at both its ends by welding flanges (15) (23), forms the cylindrical toroidal zone (19) and this zone is used for overheating and achievement of pyrolysis reactions; the space inside the inner "cylindrical shell" forms the furnace burning area (24); a tube (12), shaped like a cylindrical helicoidal spring, located inside the burning area, with an exterior diameter of the spring d3, the ratio between d3:d5 is from 0.4 to 0.95, the tube is placed concentrically with the "cylindrical shells" (14) (20), in the interior of the tube (12) the non-catalytic steam reforming reactions are achieved, one end of the tube is coupled to the cylindrical toroidal zone (19) and another end is coupled to the intake of the "mixed burner" (11).

The furnace is heated from inside by burning traditional fossil fuels with a classic combined (double injection) burner (11) of type "gas - gas" or "liquid fuel - gas" with air forcing, located at the access opening (27) and coupled to the front plate (13) of the cylindrical furnace (25). The hot combustion gases are discharged through the discharge hole (26), located at the end of the furnace (21), directly to the burning area (22) of a "user boiler" (18). The cylindrical furnace is connected to the faceplate (17) of the water-tube burner with a coupling flange (16) located on the furnace shell. The combustion of the classic fossil fuel will provide the high temperature in the furnace required for starting up a continuous process of generating syngas and the beginning of its stable combustion. Then the classic fuel supply to the burner is stopped and the burner can operate on the continuous flow of syngas. The double mantle/jacket of the furnace acts as a radiant heat exchanger with continuous supply and discharge, where the complex gaseous mixture is heated, in a continuous flow, to a temperature of 1100 to 1200 ^° C by thermal transfer of the heat from the combustion gases in the furnace burning area (24) via the inner shell wall (14) of the furnace. The movement of the complex gaseous mixture is achieved in a direction parallel with the combustion gas. As a result of this high heating process, the hydrocarbon droplets from the mixture are subjected to "primary" and "secondary" pyrolysis reactions, after which takes place their thermal decomposition into carbon, hydrogen and other new hydrocarbons that have a relatively higher stability at these temperatures. In this phase the steam in the mixture acts to prevent the coking effect which can occur as a result of "secondary" high-temperature pyrolysis. This is done by the fluidization of the carbon in the zone where pyrogenic reactions take place and at the same time by carrying out the endothermic reaction of decomposition of a portion of the steam from the mixture into so-called "water gas" C + H ₂ 0 = CO + H ₂ after which carbon monoxide and hydrogen is obtained.

The complex gaseous mixture thus formed is composed in general of hydrogen, carbon monoxide, different newly formed hydrocarbons, and the rest of the steam. It is fed into a reforming tube (12), which is located in the burning area (24) of the furnace. The reforming tube (12) plays the role of a radiant heat exchanger of high temperatures with continuous feeding and discharge of heat. Its construction consist of a tube shaped as a cylindrical coiled (helical) spring disposed concentrically within the "cylinder liner" (14) (20) of the furnace shell. The space inside the reforming tube (12) is the technological zone for achieving reforming reactions of hydrocarbons with steam at high temperatures. The complex gas mixture, during the movement through the reforming tube, opposite to the burning gases direction, is overheated to a temperature at which hydrocarbons start to undergo non-catalytic reforming, at about 1400 to 1600 °C. It is achieved by the transfer of heat from the hot gases in the flame. As a result, after the completion of the non-catalytic steam-reforming reaction of new hydrocarbons at high temperatures from complex gas mixture, formed in the previous stage of pyrolysis, C _n - _x H„-2y + (n-x)H ₂ 0 <→ [n-x+(n-2y)/2]H ₂ + (n-x)CO and the conversion reaction of carbon monoxide with steam (temperature being high enough only for a part of the carbon monoxide)

CO + H ₂ 0 <→ H ₂ + C0 ₂ at the exit of the reforming tube syngas is obtained in a continuous flow. It is generally composed of hydrogen, carbon monoxide, carbon dioxide, with a high ratio of hydrogen/carbon monoxide.

Since in the complex gaseous mixture, formed in the "rotating cavitation/vaporization device" (6), the amount of water vapor is in a stoichiometric excess to the requirements of the steam reforming reaction of the primary hydrocarbon, the syngas obtained according to the process of the present invention has a high ratio of hydrogen/carbon monoxide. The excess amount of steam from the gaseous mixture is sufficiently high as to reform, during the technological process, the primary hydrocarbon close to completely into H ₂ and CO. The steam is also enough for converting part of the CO into C0 ₂ and H ₂ . Thus, the ratio of H ₂ to CO in the obtained syngas is brought to a maximum. The dimensions of the furnace casing, of the reforming tube and the amount of complex gaseous mixture delivered from "rotating cavitation/vaporization device" must be linked in such a way as to enable a level as close to 100% of the reactions involved in the process of obtaining syngas. A positive role in time reduction needed for these reactions is the fact that the complex gaseous mixture represents a very fine and uniform dispersion of the hydrocarbon droplets in the water vapor, obtained as a result of the "micro-cracking", the intense mixing effect and the gasification via cavitation performed in the "rotating cavitation/vaporization device".

Through a pipe (9) syngas obtained this way is directed to the mixed burner's supply system (11) to be lit and burned as an alternative gaseous fuel. Temperatures for the pyrolysis and reforming reactions at the start of the syngas production process is provided in the first phase by supplying ,via a pipe-line (10), classic fossil fuel (liquid or gas), and its combustion in the mixed burner (11) for a period of time of 2-3 minutes. After the ignition and start of the stable combustion of the obtained syngas, classic fossil fuel supply to the burner is interrupted. The system of syngas production and combustion is stabilized in terms of heat balance, the preparation of the syngas passes in self- maintaining continuous flow mode, and the heat obtained from its burning is used:

- within the cylindrical furnace (25) for maintaining the high temperature necessary for the technological process of syngas production

- inside the "user boiler" (18) to produce heat (steam and/or hot water boiler), electricity or mechanical work ( done via an assembly of a steam boiler, a steam turbine, a power generator or a steam engine).

Since the temperature of the combustion flame of a syngas is over 2000 °C, used materials must withstand these temperatures for extended periods of time.

Starting the process for obtaining syngas, in a continuous flow, from room temperature until the time of its combustion, according to the present invention, is performed in minutes (typically 2-3 minutes). This is the time it takes for the "rotating cavitation/vaporization device" (6) to enter into the optimal operation regime (production of the gaseous mixture). This is also the time it takes to overheat (by burning classic fossil fuel) the technological zones (12) and (19) up to the temperatures necessary to achieve the reforming and pyrolysis reactions. Stopping the formation process of syngas is done instantly by turning off power to the electric motors that drives the "rotating cavitation/vaporization device" (6) and water pump (4). As a result the production of the gaseous mixture instantly stops, a raw material from which syngas is produced.

As a result of burning syngas with oxygen from the combustion air, the waste gases discharged from the "user boiler" (18) are generally composed of a gaseous mixture of water vapor and carbon dioxide, which is in the free state. With a steam separation/condensing plant (not shown), free carbon dioxide can be separated from waste gases. The water obtained by the condensation of steam is directed to the water tank (not shown) and can be used again as a raw material in the production of syngas. Carbon dioxide can be captured or released into the atmosphere. The whole process of obtaining and safely burning of syngas can be properly automated.

An example of a cylindrical furnace execution and of process parameters executed in installation according to the invention, which functions on the water/biodiesel mixture is presented in Table 1.

In Table I are presented the working parameters of the technological process applied, according to the invention, to an installation. This installation is using a water/biodiesel mixture.

Table I

INDUSTRIAL APPLICABILITY The invention can be used in the thermo energetics industry and refers to a multi phasic technological process of obtaining syngas, through successive operations of: cold

"cavitation"; pyrogenic reaction; non catalytic reforming with steam at high temperatures of complex hydrocarbons (heavy fuel oil, light liquid fuels, diesel, tar, naphtha, mineral oils, shale oils, vegetable oils, biodiesel, etc.) and also their wastes. After the syngas is obtained it is used as an alternative gaseous fuel in the production of thermal, electrical and/or mechanical energy.